- use the geometric normal to apply the shadow bias. This affects
cascades > 0 and spot/point lights.
- use the scene's origin as a reference point for stabilizing the
shadowmap, this is more robust.
- clamp directional shadowmap correctly to the 1-texel border, which
needs to be reachable, as it is a valid value.
- don't snap the shadowmap to texel boundaries if stable mode is not
active (before we only didn't do it based on lispsm). Stable mode can
make the shadow unstable when both the camera and the scene move
together, so it's better to have a more predictable API where
"stable" mode means that the snapping occurs and doesn't otherwise.
- add "far origin" distance slider to the debug ui
FIXES=[299310624]